1. Field of the Invention
The present invention relates to a method and apparatus for changing the spiral stitch path in a tubular fabric.
2. Brief Description of the Background of the Invention Including Prior Art
Tubular textile goods are as a rule manufactured on circular knitting machines, wherein a plurality of knitting needles are disposed on the perimeter of a cylinder and are actuated in a cyclic succession wherein each needle forms one stitch. In the process, the yarn is moved in the circumferential direction and there is an axial advance by the distance of approximately one stitch width. If the machine has one hundred needles on the perimeter, and the stitch width is 1 mm, then the total advance for one circuit is 100 mm. If the tubular piece lies flat, then for each outer side (front and rear) the advance will be, for example, 50 mm.
Thus, the path of the successive stitches in a tubular fabric is a spiral around the tube. For a single-color piece, if thin yarn is used, this spiral configuration would not have an exaggerated appearance. However, the thicker the yarn is and the more discernible the individual "cross runs" are, the more problematical is the spiral configuration, particularly when there are contrasting differences in brightness or color such as are present in fashionable horizontally striped tubular knitwear, such as hosiery, sweaters, and other garments.
To alleviate the problem, in the past, the knit "spiral tubular piece" has been cut along a longitudinal line, wherewith the entire piece was folded over in a plane and the cut edges were mutually shifted by the distance of one pitch of the spiral. The cut edges would then be sewn together. The piece would then be further processed, as be being sent to the cutting table, on a single surface.
This is a satisfactory procedure in small-shop production and manufacturing, but in machine knitting it occasions substantial expense and decreases production capacity. Therefore, it is unsuitable for large-scale factory use. Because the form of such a textile piece is so unstable, because it is difficult to align and keep aligned before it is sewn back together, in practice, it has been nearly impossible to completely remove the slant when joining the stripes so as to produce items of clothing, wherein the transverse, and in particular the cut edge, has been in accurate alignment at the cut edge.
The company ELTROTEC Elektro-GmbH, P.0. Box 1241, D-7060 Schorndorf, provides a fasop catalog issued in October 1985 and illustrating elements useful for constructing opto-electronic installations. Furthermore, the company ERNI+CO AG, Elektro-Industrie, CH-8306 Bruttisellen (Zurich) furnishes flyers dated October 1986 relating to set point - actual value comparison testing in production situations.
The company bitexma Maschinen- und Anlagenbau GmbH, D-7944, Herbertingen, Federal Republic of Germany, provides a catalog relating to a machine to correct the spirality in striped tubular knitted fabrics, issued in September 1987.